Cataract is the leading cause of blindness worldover. Diabetes is one of the major risk factors for cataractogenesis and aldose reductase (AR) has been reported to play an important role in sugar-induced cataract. In the present study, the AR inhibitory activity of Ocimum sanctum (OS), Withania somnifera (WS), Curcuma longa (CL), Azadirachta indica (AI) were studied together with their effect on sugar-induced cataractogenic changes in rat lenses in vitro. Aqueous extracts of the plants, procured from Dabur, India, were reconstituted with double distilled water to make various dilutions. AR inhibitory activity of these extracts and their anticataract potentials were evaluated in vitro in rat lenses. AR inhibitory activity of the aqueous extract of different plants was calculated considering the AR activity of normal rat lenses as 100%. The concentration of the plant extract that showed maximum AR inhibitory activity was selected to further study its effect on galactose-induced lens swelling and polyol accumulation in vitro. All the four plants were found to inhibit lens AR activity but to different extent. From dose-response curve, OS was found to be the most effective AR inhibitor followed by CL, AI and WS. The IC(50) values of OS, CL, AI and WS were calculated to be 20, 55, 57 and 89 microg/ml, respectively. OS showed a significant inhibition (38.05%) in polyol accumulation followed by CL and AI (28.4 and 25.04%, respectively). WS did not show any effect on polyol level in rat lenses. None of the plant extracts showed any significant effect on lens water content.OS possesses a significant anticataract activity in vitro and its anticataract potential could be related with its AR inhibitory effect.